Theorem 2 (Hausdorff-Bernstein-Widder theorem [1]}) 
A function f(t) is CM iff there exists a non-decreasing and bounded Borel measure \(\mu (x)\)  on \([0, +\infty )\)  such that
\(f(t)=\int e^{-xt}d\mu (x). \) 

